RADICAL REACTIONS OF N-HETEROCYCLIC COMPOUNDS .15. RADICAL INTERMEDIATES AND END-PRODUCTS OF THE OXIDATION OF 3-ANILINO-1,5-DIPHENYLPYRAZOLES WITH PB(OAC)(4)

Substituted 3-anilino-1,5-diphenylpyrazoles 1a-i were oxidized with Pb (OAc)(4) in benzene or CH2Cl2 solution. The ESR measurements confirmed the formation of aminyl radicals 3f-i from para-CH3 substituted pyraz oles 1f-i. The radical intermediates from unsubstituted pyrazoles 1a-e were assigned to triarylaminium cation radicals 6a-e. These were gene rated by consecutive oxidation of the dimeric products 4a-e whose stru cture was proven by NMR spectroscopy and N-15 labeling.